1. Field of the Invention
This invention relates to a device for the treatment of symptoms associated with carpal tunnel syndrome.
2. Background and Prior Art
The complex of symptoms resulting from compression of the median nerve in the carpal tunnel is referred to as carpal tunnel syndrome.
A cross-section of the carpal tunnel, (indicated at 20 in FIG. 2) demonstrates the vulnerability of the median nerve. The carpal bones which are tightly bound together form the dorsal medial and lateral walls of the tunnel. These bones are joined anteriorly by the transverse carpal ligament, a dense, non-resilient structure. The carpal tunnel contains the median nerve as well as nine flexor tendons and their tendon sheets.
A number of conditions such as obesity or pregnancy can increase the contents or decrease the size of the carpal tunnel and thereby compress the median nerve. Anomalous overdeveloped muscles may also compress the median nerve. Similarly, any condition that produces edema in the hand and wrist may cause or accentuate carpal tunnel compression.
The most common pathologic finding among patients with carpal tunnel syndrome is non-specific tenosynovitis. This condition is characterized by thickening of the tenosynovium, which increases the volume of the structures within the carpal tunnel thereby compressing the median nerve. A non-specific thickening of the tenosynovium is the most common cause of carpal tunnel syndrome. A patient with carpal tunnel syndrome usually first complains of pain and numbness in the fingers of one hand. At times, a patient may complain of pain extending into the forearm or even the upper arm or shoulder. The discomfort can range from mild to excruciating. If carpal tunnel syndrome has been present for several months or years, patients may also complain of clumsiness and weakness in the hand which makes it difficult for them to pick up and hold small objects. These symptoms often result from atrophy of the thenar muscles; these muscles are supplied by the motor branch of the median nerve.
If carpal tunnel symptoms are mild and of short duration (2 or 3 months), conservative treatment is usually recommended. This is particularly true when the symptoms are expected to disappear in the foreseeable future (e.g., termination of pregnancy or change of occupation). Conservative treatment includes medications such as non-steroidal anti-inflammatory drugs, steroids or diuretics, immobilization and steroid injection of the wrist. Elsey, in U.S. Pat. No. 4,854,309 (col 1, lines 11-16) suggests that exercise can be used to overcome problems associated with carpal tunnel syndrome. Unfortunately, no examples of such exercises are presented. The patent teaches the use of a wrist splint to treat the symptoms of carpal tunnel syndrome.
Non-operative treatment may provide early symptomatic relief of carpal tunnel syndrome, but often fails to give protracted benefit. This is particularly true for the individual whose job requires constant repetitive wrist and hand activities. Surgical treatment is indicated when nonoperative management is ineffective and symptoms are of sufficient severity to warrant surgery. Surgical intervention involves dissection of the transverse carpal ligament. The incision may cause injury to one or more of the small cutaneous branches of the median nerve which can result in neuroma formation or a painful hypertrophic scar. Anomalies of the median nerve are not uncommon and small incisions that will require blind dissection to decompress the nerve are fraught with significant potential complications. The complications of surgery have been documented (for a summary of complications, see, for example, "Complications of Surgical Release for Carpal Tunnel Syndrome," Rodney McDonald et al Journal of Hand Surgery, Vol. 3, No. 1 pg. 70 (1978) and include imcomplete division of the transverse carpal ligament, damage to the palmar cutaneous branch of the median nerve, palmar hematoma, and other nerve injuries.
In view of the foregoing complications of surgery, it is desirable that a device and method for treating symptoms of carpal tunnel syndrome which is both conservative and applicable towards both early and more advanced states of the syndrome should be available. Greenfield, in U.S. Pat. No. 4,750,734, teaches the construction and use of a hand exerciser. The exerciser generally comprises a regular array of openings in planar elastic member through which openings the fingers and thumb may be inserted. The fingers may be moved relative to one another against the resistance of the elastic member to exercise various muscle groups. Greenfield's device has a stiff or rigid circumferential border. This is necessary for performing exercises requiring flexion of the fingers. The rigid outer border prevents folding of the device and substantially reduces its portability in, for example, a purse or pocket.
Williams, in U.S. Pat. No. 4,730,827 describes a similar exercise device comprising a disk-like member provided with recesses in its periphery and at least one aperture for the thumb. The device has the capability of either individually or simultaneously exercising or manipulating all digits of a patient's hand thereby strengthening the muscles and tendons. Surprisingly, until now it has not been recognized that a particular set of exercises as will be described below may be performed on hand exercising devices similar to the prior art devices above to provide relief for the symptoms of carpal tunnel syndrome.